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Re: Coaxial dipole

Posted by Donald North (M) on April 11, 2007 at 18:23:11

In Reply to: Coaxial dipole posted by AJinFLA on April 11, 2007 at 17:33:01:

Yes, real life has floor reflections, but they are already captured in the recording. If one deems the goal of hi-fi is to accurately reproduce the recording in room, at the listening position, then the floor reflection from the speaker is an immediate deviation from this goal. Read some of Robert Greene's articles in The Absolute Sound. Here are a few from his website:
http://www.regonaudio.com/Gradients.html
http://www.regonaudio.com/SpendorSP12Loudspeakers.html
http://www.regonaudio.com/Snell Type B Loudspeakers.html

To reduce the floor reflection in a speaker requires a radical design. Linkwitz's Phoenix will encounter the usual ~300Hz floor dip, ~600Hz peak, etc., comb filtering from the floor reflection because a dipole is only ~3dB down at 37 degrees off axis, the angle of the floor reflected sound with a typical 36" tweeter height and ear height, and 96" listening distance.

I believe and people who have heard my Sequence speakers concur that they have excellent clarity. This is due to a few reasons:
1. Narrow dispersion with reduced floor, side wall, and ceiling reflections
2. Choice of midrange driver. In all my years as a speaker designer, it is the only midrange which nearly perfectly reproduces an impulse response as measured with MLSSA, among other attributes. No metal cone midrange I've tested can remotely make a similar claim.
3. Because of the choice in midrange driver, I run them higher than normal in frequency before crossing over to the tweeter.
4. Also because of the choice in midrange driver, its crossover is simple with minimal components and added attenuation. No metal cone midrange I've tested can make a similar claim.

Dipoles do have a spacious soundstage, but I believe it is less accurate to the recording. Listen to your speakers outdoors and hear the difference due to the room.

Quad's current generation electrostatic speakers also are designed to function as dipole point sources.

Donald North

This post is made possible by the generous support of people like you and our sponsors:

Atma-Sphere Music Systems, Inc.

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